Piston rings data

Piston rings for an automotive engine are produced by a forging process. The inside diameter of the rings manufactured by the process is measured on 25 samples, each of size 5, for the control phase I, when preliminary samples from a process being considered 'in control' are used to construct control charts. Then, further 15 samples, again each of size 5, are obtained for phase II.

data(pistonrings)

Format

A data frame with 200 observations on the following 3 variables.

diameter

a numeric vector

sample

sample ID

trial

preliminary sample indicator (TRUE/FALSE)

References

Montgomery, D.C. (1991) Introduction to Statistical Quality Control, 2nd ed, New York, John Wiley & Sons, pp. 206--213

Examples

data(pistonrings)
describe(pistonrings, by = trial)
#> ── trial = FALSE ─────────────────────────────────────────────────────────────── 
#>          Obs  Mean  StdDev   Min Median   Max
#> diameter  75 74.01 0.01241 73.98     74 74.04
#> sample    75 33.00 4.34959 26.00     33 40.00
#> 
#> ── trial = TRUE ──────────────────────────────────────────────────────────────── 
#>          Obs Mean  StdDev   Min Median   Max
#> diameter 125   74 0.01007 73.97     74 74.03
#> sample   125   13 7.24012  1.00     13 25.00
boxplot(diameter ~ trial, data = pistonrings)

plot(diameter ~ sample, data = pistonrings, cex=0.7)
with(pistonrings, lines(tapply(diameter,sample,mean)))